1. Technical Field
The invention relates generally to image processing systems, and, more particularly, to image processing systems that allow a user to create and view panoramic three dimensional images from data representing multiple views of a scene.
2. Description of the Related Art
Conventional three dimensional graphics applications and associated hardware render scenes composed of one or more three dimensional objects. The objects are typically represented by geometric primitives, for example triangles. The objects are represented by graphics data that represent the position and color of primitives in a model coordinate system. The graphics system renders the scene to display those object(s) of the scene that are visible in a viewing window based upon a view point. The user can navigate through the scene by changing the position and orientation of a view point reference (camera). In addition, animations can be performed by navigating through a series of preselected positions and orientations of the view point reference.
The rendering operation is a computationally intensive process and, thus, typically performed by specialized graphics hardware. Such systems are powerful yet remain costly due to the need for specialized hardware dedicated to this purpose.
Moreover, conventional three dimensional graphics systems require that the user provide a three-dimensional model of the scene (i.e., graphics data that represents the position and color of the geometric primitives of the scene in the model coordinate system). Such models may be created with software in conjunction with peripheral devices (pen tablets, scanners, cameras, etc). For example the software sold under the name CATIA by Daussault of France allows a user to build a three-dimensional model of a scene. However, such modeling software is expensive and, in addition, a significant investment in labor may be required to model even a relatively uncomplicated scene.
Because of the high costs associated with conventional three dimensional graphics systems, alternative solutions have emerged that provide effective yet limited capabilities in creating and viewing a three dimensional scene which are suitable for use on standard personal computers and without the need for dedicated graphics hardware. One such solution is the software developed and sold by Apple Computer, Inc. of Cupertino, Calif. under the name QuicktimeVR. The QuicktimeVR software is segmented into two distinct packages. The first package, which is sold to content providers, is an authoring tool that allows content providers to develop a panoramic three-dimensional image from multiple views of a scene. The second package is a viewer which is distributed to consumers and which allows the consumer to view the panoramic three-dimensional images created by the authoring tool. A more detailed description of the operation of the QuicktimeVR system may be found in Chen, "Quicktime.RTM. VR--An Image-based Approach to Virtual Environment Navigation", SIGGRAPH 1995, Los Angeles, Calif., pp. 29-38, and in U.S. Pat. No. 5,396,583 to Chen et al., which is assigned to Apple Computer, Inc.
The QuicktimeVR system utilizes a cylindrical environment map to represent the panoramic view of a scene (or collection of images). Different perspective views are rendered by mapping the cylindrical environment map to a desired viewing window.
A hotlink is an area of the panoramic scene that is associated with an action. For example, the action associated with hotlink may be the loading and displaying of a second environment map, the generation of a multimedia event such as an audio clip or video clip.
The QuicktimeVR system provides for hotlinks to be integrated into the panoramic scene. The location of such hotlinks are made evident to the user by a changing cursor shape in the display window when the user moves the cursor over an area of the scene that is associated with a hotlink. This method is limited because it requires the user to navigate throughout the panoramic scene in order to locate the hotlinks integrated into the scene.
Thus, there is a need in the art to provide for a more effective system for integrating hotlinks into three dimensional panoramic images, and thus provide an improved level of interactive graphical feedback.